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Roger Mazengarb

Navigation Question ????

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Hi Guys,I know this question may appear to be a bit stupid..... (I....probably am!).............but I'm trying to understand aircraft proticol and systems.Can someone explain to me the difference between the COURSE display and the HEADING display on aircraft glare panels.??????On the DC9 panel (for example) .......although I can change the COURSE digits on the Glare Panel, I don't quite understand how this relates to any aircraft system???When I change the HEADING digits the aircraft responds and changes direction. Could someone please explain to me what the function of these COURSE digits are and how they should be used to aid navigation. I hope you understand what I mean.Many Thanks to you allRegards John

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John,HDG sets the heading the aircraft will follow when the autopilot is coupled to the heading bug on the HSI or gyro compass. CRS sets the course the aircraft will follow when coupled to a VOR - in the same manner as dialing in a course on a VOR, you would set the radial with this knob.

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Hi Randall,Thanks for the explanation and reponse............When you talk about coupled to a VOR........Could you please explain how I would do this??If I input a COURSE (eg. 260 degrees) into the CRS display on the glare panel, how do I get the aircraft to follow that course??Just to let you know Randall, I have read the FLY manual (Many times) any completly understand the VOR indicators once the Frequency has been dialled in,.......I'm just confused about the function of the CRS display........I'd like to know how the aircraft responds to the CRS input once a Pilot has dialled in a course. If anyone could give me an working example.........I'd really appreciate it.RegardsJohn

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John,OK - Here are some examples of various setups for VOR navigation in different planes and their basic function:1. Malibu - It doesn't have the EFIS system of more sophisticated planes: it uses a standard HSI. The HSI functions as a VOR and course deviation instrument:--Dial in the frequency on the Nav 1 radio for VOR 1--Turn the Course dial on the HSI. To fly directly to the VOR, turn the dial until the "needle" joins together and becomes a straight line - that's your immediate "TO" course. Turn the aircraft to that heading or press the NAV button on the AP.--To fly a specific radial to or from turn the Course dial until you have that radial selected. Turn right or left, mattering which side of the path the needles are on - try to intercept at around 30 degrees. When the needles begin to move together, turn on NAV on the AP - the plane will turn onto that radial as the needles join.EFIS systems do exactly the same thing, but because they are electronic displays, the different modes of operation are selected on a remote panel, sometimes on the glare shield, but not always. Here are some examples of different EFIS systems represented in the Fly!2 world:2. Pilatus:--Dial in the frequency on the NAV 1 radio for VOR 1--Push the System Bearing Pointer on the EFIS control until NAV 1 indicates in the Navigation Display CRT--Turn the Course knob on the EFIS control and set it in the same manner as the Malibu mechanical system--Navigate manually or via AP in the same manner as the Malibu3. Hawker:--Set the frequency for VOR 1 on the radio panel--Turn the EFIS Course Source to VOR 1--Turn the Course knob to select your course (align the electronic needles for direct or select a course to use).--Navigate manually or via NAV mode on the APAlso, the Hawker's Multifunction display can be used as an electronic VOR:--Set the proper frequency on the radio panel--Turn the Display Format knob to VOR 1 or VOR 2--Turn the Course knob to set the course--Fly manually to align the "needles"

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Hi RandallThanks very much for the examples........I fully understand the principals involved now!! and can work out how the systems interact with each other.Thanks again for your time and wonderful explanations.Kind regardsJohn

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You're quite welcome - the choices can be confusing! The main thing to remember is the mode of operation will limit which controls are usable:--FMS/WAYPOINT Mode: The System follows the flight computer's flight plan path - both HDG and CRS are inoperative--VOR/ADF Mode (HDG selected on the AP): The system follows the heading set on the DG/HSI/Nav display - HDG knob is operative, but CRS knob is not--VOR/ADF Mode (NAV selected on the AP): The system follows the selected VOR radial for VOR1 - the CRS knob is operative, but the HDG knob is not

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Hi Randall................thanks again for all your help, One thing I forgot to mention regarding NAV systems was on the HAWKER.On the PFD switches to the left of the ADI/HSI..............theres one which reads PFD NAV SYSTEM. Although the switch appears to function, I can't see any change in the aircrafts flight patterns or indeed any change to Panel instrument or displays.Do you....(or anybody else) happen to know what this switch is for????Kind RegardsJohn

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John,I don't believe this one functions - the other two (AOA and FD Bars do function). I would guess that the Nav switch is to switch betwwen the course tracks as a display on the PFD in some manner.I'll have to check it out again when in flight, but I don't believe it was ever activated.

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G'day John,Seems as I'm on a different time frame here in Aus so I'll give an answer.Mate the swith is a source transfer switch. It determines which nav radio the PFD is using.The switch will display a vertical glide slope scale and horizontal course deviation scale, both on the PFD. (provided the respective radio is tuned)To see how it works try this.1. With the aircraft on the ground (all powered up) set both the pilots and copilots PFD NAV switches to #1. The PFD at this stage will not be displaying any ils info.(because the captains radio isn't tuned)2. Now on the Captains radio (nav 1) tune in an ILS freqency for the airport you are at. Immediately both the Captains and copilots PFD's will display the ILS info.3. Now switch the copliot's PFD NAV SYSTEM to #2. The captains PFD will remain unaffected as it is still using Nav #1 radio as it's source, but the glideslope and deviation scales on the copilots PFD will no longer be displayed as we haven't tuned the NAV #2 radio to an ils.What this means is that either pilot can fly the aircraft using either the NAV #1 or NAV #2 radio to display information on their respective PFD's/Hope this helps.Cheers,Roger @YSSY

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G'day Randall,Sorry to go over the top of you but when I started my post yours wasn't here. The swich simply switches the radio used for ILS information displayed on the PFD.Sincere apologies.Cheers,Roger @YSSY

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Thanks Roger. I figured as much, but I had never attempted to switch it out in flight - glad to hear it works!

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Guys,Iam getting confused now.I thought the course is the direction the plane is flying and the heading is the direction the nose of the plane is pointing. The difference is the result of crosswinds.:-hmmm

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You're correct - what we're talking about here is how those control settings (heading and course) are used by the autopilot when coupled for navigation.Heading (HDG)When Heading mode is used on a plane with an EFIS system, the Heading knob on the EFIS control panel rotates the heading bug on the display - the AP then places the nose of the aircraft on that heading and holds it. The actual course of the aircraft over the ground will matter on the wind strength and direction.Course (CRS)When Nav mode is used on a plane with an EFIS system and the Course Source is set to VOR1, the Course knob changes the course to or from the tuned station and is represented on the display. The AP then follows that course, automatically compensating for winds.

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Hi Roger.......how are things down under??Thanks for the superb explanation.............this forum is a great community and has a fantastic wealth of information.....if only more people would dare to ask questions...........I'm sure we'd all learn a bit more about this excellent sim and general aviation, as I'm sure many have done from yours and Randall's input.Thanks Guys for taking the time to explain.Kind RegardsJohnThe only bad news is,............ I've a lot more questions to ask!!

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